Radar systems of the prior art typically position a single feed at the antenna focal point. Such antennas further are designed to optimize beam collimation and focusing with respect to the focal point. This generally limits the antennas of the prior art to a single antenna feed, and makes them generally unsuited for multimode applications.
There are known exceptions to the single feed at the focal point approach, but these are generally expensive approaches, which additionally frequently require the acceptance of degradation in gain and resolution. Such approaches include phased array sources, and Luneberg lenses, and extended feed systems.
Accordingly, it is an object of the instant invention to develop a multiple feed microwave antenna in which the feeds are positionable at a distance removed from the focal point of the antenna.
It is a further object of the invention to establish a high gain multiple feed antenna arrangement in which the antenna feeds are removed a distance from the focal point of the antenna.
It is a further object of the invention to develop a multimode antenna which can provide more than one antenna function or mode using a single shared antenna aperture.
It is a further object of the invention to develop a relatively compact, inexpensive, and reliable off focal-point antenna feed arrangement for multimode microwave radar application.
It is a further object of the invention to develop a new and improved multimode off focal-point antenna feed arrangement which is particularly suited for millimeter and submillimeter wavelength radar application.